Sound amplifying device



July 14, 1931. E. F. CASSEL 1,814,022

SOUND AMPLIFYING DEVICE Filed March '7, 1925 2 Sheets-Sheet l July 14,1931. E. F. CASSEL 1,814,022

SOUNb AMPLIFYING DEVI CE Filed March 7; 1925 2 Sheets-Sheet 2 I J g Z0 Patented July 14, 1931 PATENT OFFICE ELMER I. OASSEL, OF WASHINGTON, DISTRICT OF COLUMBIA SOUND AMPLIFYING DEVICE Application filed Iarch'7, 1925. Serial No. 18,803.

This invention is a sound amplifying device of the type popularly termed loud speakers for radio receiving apparatus, but is not limited to such use.

One of the objects of. the invention is to provide means whereby sound may be uniformly disseminated and controlled. A further object is 'to provide 'a device of the character mentiohed, which is adjustable with relation to the volume of sound received or the volume of sound to be discharged, or both. A further object is to provide means whereby sound from the same source may be distributed through separate. pneumatic channels to different specific points, such channels being capable of conjoint or inde-- pendent operation, as desired. A further object is to provide means whereby standard ear phones may be used conjointly with or independently of a loud speaker sound producingelement.

The invention will be hereinafter fully set forth and particularly pointed out in the claims.

In the accompanying drawings Figure 1 is a longitudinal sectional view illustrating a radio loud speaker with the invention applied thereto. Figures 2 and 3 are similar views illustrating slight modifications. Figure 4 is a detail view of another modification illustrating a method of attach ing ear phones to the sound box of the device. Figure 5 is a detail view illustrating a modification of the sound-conveying tube. Figure 6 is a view illustrating a simplified ap plicat-ion of the invention.

Referring to Figure 1 of the drawings, 10 designates a sound amplifying device con sisting of a casing of circular cross section open at one side, the wall being shaped to provide a parabolic sound-wave reflecting surface. Said casing is supported by means of a suitable standard. lVhile it is preferred to construct the casing of a contour which is cylindrical in cross section, and parabolically curved in longitudinal section, the invention is not limited to such contours.

The smaller end of the casing 10 isprovided with a flange 11, surrounding an opening positioned at the longitudinal axis or focal point of the said casing, and extended through said flange is a sound-conveying tube 12, preferably of circular cross section, having its outer end connected with a sound reproducing elcment 13, such as is commonly provided for radio loud speakers, the wires 14 and 15 leading to the radio receiving set.

The delivery end of the tube 12 is shown as flared, as indicated at 16, so as to amplify sound passing through the tube; but may be of the shape illustrated in Figure 5. Said tube is provided with a spider 17, in which is concentrically mounted an axially adjustable sound distributing vdevice 18. Said sound distributing device is illustrated as comprising a body of approximately conical or frusto-conical shape, but is not limited to such shape. As shown, the distributing device 18, has its apex provided with a threaded extension to engage the spider 17 and the enlarged portion is positioned to extend across the enlarged end of the tube 12, so as to intercept sound waves being delivered by said tube.

In practice, the sound conducting tube 12 is slidably mounted in the flange 11 in such manner that it may be adjusted longitudinally to cause the outlet end 16 of said tube to approach or recede from the common focal point of the inner longitudinal sectional curve and center of the inner cross section casing 10. Said tube 12, however, is so supported that no matter to what extent it may be adjusted'longitudinally, it is held against lateral displacement and is always maintained concentrically with respect to the casing 10. The sound distributing device 18 is preferably circular in cross section and of longitudinal section proportioned with relation to the outlet 16 of the tube 12. In operation, the 99 said member 18 is adjusted with relation to the outlet end 16 of the tube 12, to a position which will cause it to deflect and distribute sound waves as they are discharged from the outlet of the tube 12, causing said waves to be diverted laterally'and to directly impinge against the reflecting inner surface of the easing 10. It will be particularly noted that the sound waves are diverted in an angular di-' rection, and are caused to directly impinge against the surface in a manner to secure a maximum amplification effect of the parabolic surface.

In the form illustrated in Figure 2, the amplifier 10' is practically the same in construction as that illustrated in Figure 1. In this construction the sound producing -element 13 is supported by a fixed extension 20. slidably mounted in a sleeve or collar 21, carried by a spider 22, extending transversely across the casing 10. -A sound-conveying tube 12 extends from the sound producing element 13 and is provided with a flared discharge end 16. contiguous to the focal point of the reduced end of the casing 10. The sound distributing device 18 is of the same contouras described in Figure 1, but in this form of the invention is mounted upon a threaded stem 23, which is adjustably mount-- ed in the-casing 10.

In operating the device illustrated in Figure 2, the focusing of the sound waves is effected by relative adjustment of the extension 21 and the member 18, with respectto each other and with respect to the focal point of the casing. The arrangement is such that the reduced end of the focusing device extends into the flared opening 16, and sound waves delivered at such opening are angularly deflected by the focusing device, and are caused to impinge directly against the parabolic amplifying surface of the casing 10".

A further modification is illustrated 1n Figure 3, in which the parabolic sound reflecting casing 10 is the same as that iilustrated in Figure 1. Said casing is provided with a flange 11", in which is slidably mounted a tube 12", having its delivery .end flared as indicated at 16", the reduced end of the distributing device 18 being adj ustably mounted therein as in Figure 1 The outer end of the tube 12 is connected with a sound chamber 25, which is rovided with a tubular'extension 26, slida ly engaged by a flange 27, at-

tached to the sound roducing element 28. Adjustably mounted in the chamber 25 is a cut-off slide 29, which may be moved across the inlet end of the tube 12 to prevent sound from passing into the parabolic reflecting chamber 10". The chamber 25 is also provided with a nipple 30, in which is removably mounted a tubular coupling member 31, provided with branches 32, to which are secured flexible ear tubes 33.

By the arrangement illustrated in Figure 3 all of the focusing advantages of the structures illustrated in the other twofigures are obtained, but the construction has the additional advantagethat it is unnecessary to use the electric car phones for tuning in, because the ear tubes 33 may be used for that pur-' pose. ,This device obviates the use of electric switches for connecting a loud speaker, with the very marked advantage ofnot disturbing delicate tuning adjustments of the receiving By this arrangement means are provided by which a number of persons may listen in to the reception of sound from the device 28, without necessitating ,the expense of electric car phones, and without the dissipation of electric currents through a multiplicity of.

electric ear phones:

Figure 4: illustrates a modification by means of which a multiplicity of sound producing elements may be used in connection with a sound amplifying casing, such as illustrated in the other figures of the drawing. Referring to said Figure 4, a chamber 25*, similar to that illustrated in Figure 3 is provided with a suitable opening to receive the usual loud speaker element 28, such as illustrated in Figure 3. Said chamber 25 is also provided with any desired number of openings, two being shown, forming seats for the reception of standard electric ear phones 35 and 36. One end of said chamber is provided with a nipple 37. to receive a forked coupling tube 38, to which are attached rub her ear tubes 39. In practice, by means of a simple electrical switch (not shown) across the circuits operating the sound reproducing elements 28 and 35 and'36, either may be used separately, as desired, thus making the ear phones available for receiving signals which are too weak for a loud speaker element, such as 28. Signals received by the ear phones may be passed through a sound-conveying tube, similar to the tube 12 of Figure 1, into the sound amplifying casing, or through the tubes 39. By this arrangement the ear phones are available for general reception through an amplifying casing, or for individual reception through the ear tube attachment. It is obvious that by multiplying the number of the ear tube 5 the sound conveying tube16 is of uniform diameter throughout its length and the distributing idevice'18. is shown as provided with its deflecting "surface of convex form.

With these exceptions this form of the invention is the same as illustrated inthe other 6 the sound conveying tube is omitted and the sound producing element is concentrically positioned to deliver the sound waves directly within the amplifying casing. Referring to said figure the amplifying casing 10 may be of any desired shape and has mounted therein the sound producing device 40, which is diagrammatically illustrated as consisting of a diaphragm a1 and an electro-magnetic actuator 42. As before stated, the sound producing device is diagrammatically illustrated and any desired form of sound producing device may be employed.

Mounted in a spider 22* is a threaded shank 43 carrying a distributing device 44 which may be of any of the forms illustrated in the other figures, the convex type being shown. In this device as in the other forms the sound waves are delivered at the point of maximum efliciency for sound distribution with, respect to the reflecting surface which is employed, and the sound distributing device causes a uniform distribution of the sound waves away from this point so as to cause them to girectly impinge against the reflecting surace.

Having thus explained the nature of the invention and described an operative manner of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all of the forms of its use, what is claimed is 1. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere at one end, said surface having an approximate focal point located within said space, means in the other end of said space and concentrically supported therein for delivering sound waves into said space at a position corresponding to the said approximate focal point, and sound intercepting means also located Within said space and separated from said sound reflecting surface, so that it will, intercept sound waves introduced into said space 'by said sound wave delivering means, said reflecting surface being shaped to divert and distribute the intercepted sound Waves in an outward direction toward said sound reflecting surface.

2. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere at one end, said surface having an approximate focal point located within said space, means in the other end of said space and concentrically supported therein for delivering sound waves into said space at a position corresponding to the said approximate focal point, sound intercepting means also located within said space and separated from said sound reflecting surface, so that it will intercept sound waves introduced into said space b said sound wave delivering means, said re ecting surface being shaped to divert and distribute the intercepted sound waves in an outward direction toward said sound reflecting surface, and sound producing means supported by said sound delivery means.

3. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere at one end, said surface having an approximate focal point located Within said space, a sound conveying tube concentrically supported within said space in the other end thereof and having its discharge end projected into said space and terminating at a position corresponding to the said approximate focal point, and sound intercepting means also located within said space and separated from said sound reflecting surface, so that it will intercept sound waves introduced into said space by said tube, said reflecting surface being shaped to divert and distribute the intercepted sound waves in an outward direction toward said sound reflecting surface.

4. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere, said space having an approximate focal point, a sound conveying tube having its discharge end located within said space in a positioncontiguous to the said focal point, a sound-distributing member located contiguous 'to the discharge end of said tube and shaped to deflect sound waves delivered thereby in alateral direction against said sound-reflecting surface, ard means whereby the position of said sound-distributing member may be varied with respect to the focal point of said soundreflecting surface.

5. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere at one end, said surface having an approximate focal point located Within said space, a sound conducting channel of varying amplitude concentrically supported within said space and having its discharge end projecting into said space and terminating at a position corresponding to the said approximate focal point, and sound intercepting means also located within said space and separated from said sound reflecting surface so that it will intercept sound waves introduced into said space by said channel, said reflecting surface being shaped to divert and distribute the intercepted sound waves in an outward direction toward said sound reflecting surface.

6. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal point, an adjustably mounted sound-conveying tube having its discharge end positioned contiguous to the said focal point, and a sound distributing member positioned to intercept sound waves delivered by said tube, and shaped to deflect said sound waves in a lateral direction against said sound reflecting surface.

7. A sound producing device com rising means providing a concave sound re eoting surface having an approximate focal point, an adjustably mounted sound-conveying tube having its discharge end positioned contiguous to the said focal point, and a sound distributing member positioned to intercept sound waves delivered by said tube, and shaped to deflect said sound waves in a lateral direction against said sound reflecting surface, said sound distributing member being adgustably mounted with respect to said tu e.

8. A sound producing device comprising a sound reflecting surface enclosing a space which is open to the atmosphere at one end, said surface having an approximate focal point located within said space, a" sound conveying tube concentrically mounted within sald space and having an enlarged delivery end projected into said space and terminating at a position corresponding to the said approximate focal point, and a sound intercepting member also located in said space and separated from said sound reflecting surface, so that it will intercept sound waves introduced into said space by said tube, said reflecting surface being shaped to divert and distribute the intercepted sound waves in an outward direction towardsaid sound reflecting surface.

9. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal point, a sound conveying tube having an enlarged delivery end positioned contiguous to the said focal point, a sound distributing member positioned to intercept sound waves de livered by said tube, and shaped to deflect said sound waves in a lateral direction against said sound reflecting surface, and means for adjustably supporting said sound delivery tube.

10. A sound producing device comprising means providing a conca've sound reflecting surface having an approximate focal point, a sound conveying tube having an enlarged delivery end positioned contiguous to the said focal point, a sound distributing member positioned to intercept sound waves delivered by said tube and shaped to deflect said sound Waves in a lateral direction against said sound reflecting surface, and means for adjustably supporting said sound delivery tube, said sound distributing member being adjustable with respect to said tube.

11. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal point, a sound conveying tube having its discharge end positioned contiguous to the said focal point, a sound distributing device at the discharge end of said tube, a sound producing element, an enclosed chamber between said sound roducing element and said tube, means or preventing sounds produced by said element from passing into said tube, and means independent of the tube for conducting sound from said chamber.

12. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal int, a sound conveying tube having its disc arge end positioned contiguous to the said focal point, a sound distributing device at the discharge end of said tube, a sound producin element, an enclosed chamber between said sound roducing element and said tube, a. shut o valve controlling passage of sound from said chamber to said tube, and a sound oulfilet for said chamber independent of said tu e.

13. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal point, a sound conveying tube having its discharge end positioned contiguous to the said focal point, a sound distributing device at the discharge end of said tube, a sound producing element, an enclosed chamber between said sound producing element and said tube, means for preventing sounds produced by said element from passing into said tube, means independent of the tube for conducting sound from said chamber, and means whereby electric ear phones may be connected to direct sounds into said chamber.

14. A sound producing device com rising means providing a concave sound re eoting surface having an approximate focal point, a sound conveying tube having its discharge end positioned contiguous to the said focal point, a sound distributing device at the discharge end of said tube, a sound producing element, an enclosed chamber between said sound producing element and said tube, said chamber having spaced apart openings in its walls shaped to receive electrical ear phones, means for reventing sounds from passing into said tube, and means independent of the tube for conducting sounds from said chamber. a

15. A sound producing device comprising means providing a concave sound reflecting surface having an approximate focal oint, a sound conveying tube having its disc arge end positioned contiguous to the said focal point, a sound distributing device at the discharge end of said tube, a sound producing element, an enclosed chamber between said sound producing element and said tube, said chamber having spaced apart openings in its walls shaped to receive electrical ear phones, means for preventing sounds from passing into said tube, and a sound outlet for said chamber independent of said tube.

16. A sound amplifying device comprising a member provided with a concave reflecting surface surrounding an enclosed s ace which is open to the atmosphere, means or causing sound waves to be delivered at a lposition within said space corresponding to t e point of maximum efiiciency for sound distribution with respect to said sound-reflectin surface, and means spaced from said soun reflecting surface for uniformly distributing said sound waves from said point and causing them to impinge against said reflecting surface.

17. The method of amplifying sound waves comprising causing the sound waves to be delivered into a s ace enclosed by a sound reflecting surface w ich space is open to the atmosphere, said sound waves being delivered at a position separated from the wall of said space, which positionapproximately corresponds to the point of maximum eificiency of sound distribution with respect to said reflecting surface, and then intercepting said sound waves and causing the intercepted sound waves to be uniformly radiated outwardly from the position of interception to said reflecting surface.

In testimony whereof I have hereunto set my hand.

ELMER F. CASSEL. 

